The present invention relates to catheters used in invasive medical procedures, and in particular to catheters with a capability to measure pressure.
Catheters are extensively used in medical procedures to probe or open restricted vascular structures or other bodily conduits, in for example the delivery of contrast dyes for radiographic procedures, balloon angioplasty to open coronary or other arteries, delivery of stents, insertion of heart monitors and ECD leads as well as numerous other procedures on humans and other living creatures.
In such catheterization procedures, it is essential that the physician visualize the location of the catheter in the body with respect to the critical tissues and other biological structures. This is usually accomplished by providing an x-ray source and an an X-ray imaging camera equipment are on opposite sides of the patient's body. The X-ray source and camera are under motorized control to precess about the patient so that images can be quickly taken from multiple different angles. Usually at least the tip of catheter is radio-opaque, typically comprising a stable barium compound as a filler. During vascular catheterization periodic and repeated injection of X-ray contrast dye from the catheter is required to visualize the blood flow around the catheter, and hence the location of the catheter tip within the arteries or veins. As the contrast agent diffuses into capillaries, it again becomes difficult to visualize the position of the catheter tip.
However, difficulties arise as the catheter technology has improved to where it is possible to probe smaller and smaller conduits or channels. However it is also easier to damage thinner tissue. Further, in arterial catheterization, as less contrast is available in thinner arteries, more contrast agent is required. In these procedures, both the physician, who is close to the patient to guide the catheter, and the patient are exposed to X-rays during the entire procedure. Although the patient receives more X-radiation during a single procedure, the skilled clinician can receive significant accumulated dose from multiple procedures.
Such catheter devices typically include a pressure sensing means at the tip to determine the local blood pressure to confirm that the device is itself is not blocking the artery being probed.
It is therefore an object of the present invention to provide an improved method for guiding catheters without the risk of damage to tissue structures.
It is also an object of the invention to provide means for catheterization that use either a lower x-ray dose and/or a smaller quantity of contrast dye.